How do I make edges on a curve have equal length while maintaining the rough shape of the curve?
To subdivide the long faces on the length of your tube you can add loop cuts. Press &#9096; CtrlR and use the scroll wheel or &#8670; Page up to increase the number of cuts being made.



If you want to subdivide the top of your tube you could use the knife tool K to mark out the path of the cuts you want to make.

Another option for the top is to use the inset tool I to add loops parallel to your profile.